1. Field of the Invention
The present invention relates to a method and apparatus for fabricating semiconductor devices, and particularly to a method and device for carrying a substrate into and out of multiple process chambers for different processings in the semiconductor device fabrication apparatus, and to a semiconductor device.
2. Description of the Prior Art
For the fabrication of semiconductor devices, there is known a sequential multi-processing system, as described in Japanese patent publication JP-A-Hei-4-63414, in which multiple process chambers for cleaning, deposition, etching, exposure of latent image, etc. are laid out to surround a transfer chamber so that various processes are implemented in ambient conditions isolated from the atmosphere with the intention of preventing the contamination of substrate surface and improving the quality of semiconductor devices.
A thermal process chamber of cluster structure including a vacuum load-lock chamber, nitride film deposition chamber, oxidation/annealing chamber, amorphous silicon film deposition chamber, and wafer vapor cleaning chamber, all connected through gate valves around a vacuum chamber equipped with a wafer transfer interface mechanism for carrying a wafer, and processing the wafer in different ambient conditions under control of wafer surface condition is described in the article entitled "Innovative Semiconductor Processing Technology in 1994" in the supplement of monthly publication "Semiconductor World", pp. 237-242, particularly in FIG. 5 on page 241.
FIGS. 2A and 2B are brief plan views of the prior art apparatus, which mainly consists of a transfer chamber 21, process chambers 22 through 29, and a substrate carriage means 32. FIG. 2A shows the apparatus, with the canopy over the transfer chamber 21 being removed, in which the carriage means 32 holding a substrate 31 is directed to face a process chamber 26. FIG. 2B shows the transfer chamber 21 and process chamber 26, with their canopies being removed, in which the carriage means 32 carries a substrate 31 into/out of the process chamber 26. The transfer chamber 21 has its interior kept at a constant vacuum state of 10.sup.-6 torr, while each process chamber undergoes the evacuation of gas down to a high vacuum state of 10.sup.-8 torr and thereafter regains the same ambient condition as of the transfer chamber at each traffic of substrate.
For the conveyance of a substrate between chambers of different ambient conditions, there is known a means of carrying a substrate on a holder through a communication corridor, prior evacuation chamber, and communication corridor, as described in Japanese patent publication JP-A-Sho-62-147726.
However, the above-mentioned prior art multiprocessing system, in which the process chambers are isolated from the transfer chamber through the gate valves, necessitates a preparation time for equalizing the interior pressure of the process chamber to the pressure of the transfer chamber at each traffic of substrate, resulting in a degraded throughput. It further involves a technical problem of the overhead time for setting up the ambient condition and stabilizing the processing condition in the process chamber at each exchange of substrates.
The above-mentioned prior art of carrying a substrate into/out of process chambers while retaining individual ambient conditions in the chambers involves a technical problem of the contamination of the substrate on the holder due to the gas leaking from the process chamber or transfer chamber into the prior evacuation chamber through the clearance between the communication corridor and substrate holder.